To better understand why onion addresses are so strange, it helps to remember that onion services don't use the insecure Domain Name System (DNS), which means there is no organization like ICANN to oversee a single root registry of onion addresses or to handle ownership dispute resolution of onion addresses. Instead, onion services get strong authentication from using self-authenticating addresses: the address itself is a cryptographic proof of the identity of the onion service. When a client visits an onion service, Tor verifies its identity by using the address as ground truth.

In other words, onion services have such absurd names because of all the cryptography that's used to protect them. Cryptographic material are basically huge numbers that look meaningless to most humans, and that's the reason onion addresses tend to look random as well.

To motivate this subject further, Tor developers have medium-term future plans for upgrading the cryptography of onion services, which has the side-effect of increasing onion address length to 54 characters! This means that in the future onion addresses will look like this:

llamanymityx4fi3l6x2gyzmtmgxjyqyorj9qsb5r543izcwymlead.onion

lfels7g3rbceenuuqmpsz45z3lswakqf56n5i3bvqhc22d5rrszzwd.onion

odmmeotgcfx65l5hn6ejkaruvai222vs7o7tmtllszqk5xbysolfdd.onion

Remembering onions

Over the years the Tor community has come up with various ways of handling these large and non-human-memorable onion addresses. Some people memorize them entirely or scribe them into secret notebooks, others use tattoos, third-party centralized directories or just google them everytime. We've heard of people using decks of cards to remember their favorite onion sites, and others who memorize them using the position of stars and the moon.

We believe that the UX problem of onion addresses is not actually solved with the above ad-hoc solutions and remains a critical usability barrier that prevents onion services from being used by a wider audience.

The onion world never had a system like DNS. Even though we are well aware that DNS is far from the perfect solution, it's clear that human memorable domain names play a fundamental role in the user experience of the Internet.

In this blog post we present you a few techniques that we have devised to improve the usability of onion addresses. All of these ideas are experimental and come with various fun open questions, so we are still in exploration mode. We appreciate any help in prototyping, analyzing and finding flaws in these ideas.

Idea 1) A modular name system API for Tor onion services

During the past years, many research groups have experimented and designed various secure name systems (e.g. GNS, Namecoin, Blockstack). Each of these systems has its own strengths and weaknesses, as well as different user models and total user experience. We are not sure which one works best for the onion space, so ideally we'd like to try them all and let the community and the sands of time decide for us. We believe that by integrating these experimental systems into Tor, we can greatly strengthen and improve the whole scientific field by exposing name systems to the real world and an active and demanding userbase.

Idea 2) Using browser extensions to improve usability

Other approaches for improving the usability of onion addresses use the Tor Browser as a framework: think of browser extensions that map human memorable names to onion addresses.

There are many variants here so let's walk through them:

Idea 2.1) Browser Extension + New pseudo-tld + Local onion registry

A browser extension like HTTPS-everywhere, uses an onion registry to map human-memorable addresses from a new pseudo-tld (e.g. ".tor") to onion addresses. For example, it maps "watchtower.tor" to "fixurqfuekpsiqaf.onion" and "globaleconomy.tor" to "froqh6bdgoda6yiz.onion". Such an onion registry could be local (like HTTPS-everywhere) or remote (e.g. a trusted append-only database).

Even an extension with a local onion registry would be a very effective improvement to the current situation since it would be pretty usable and its security model is easy to understand: an audited local database seems to work well for HTTPS-everywhere. However, there are social issues here: how would the onion registry be operated and how should name registrations be handled? I can see people fighting for who will get bitcoin.tor first. That said, this idea can be beneficial even with a small onion database (e.g. 50 popular domains).

Here is a graphical depiction of a browser extension with a local onion registry resolving the domain sailing.tor for a user:

A more dynamic alternative here involves multiple trusted remote onion registries that the user can add to their torrc. Imagine a web-of-trust based system where you add your friend's Alice onion registry and then you can visit facebook using facebook.alice.onion.

A similar more decentralized alternative could be a browser addon that uses multiple remote onion registries/notaries to resolve a name, employing a majority or supermajority rule to decide the resolution results. Such a system could involve notary nodes similar to SSL schemes like Convergence.

Idea 2.3) Browser extension redirects existing DNS names

An easier but less effective approach would be for the browser extension to only map DNS domain names to onion names. So for example, it would map "duckduckgo.com" to "3g2upl4pq6kufc4m.onion". That makes the job of the name registrar easier, but it also heavily restricts users only to services with a registered DNS domain name. Some attempts have already been made in this area but unfortunately they never really took off.

Idea 2.4) Automatic Redirection using HTTP

The Alt-Svc HTTP header defines a way for a website to say "I'm facebook.com but you should talk to me using fbcdn.com." If we replace that fbcdn.com address with facebookcorewwi.onion - then when you typed in Facebook, the browser would, under the covers, use the .onion address. And this can be done without any browser extension whatsoever.

One problem is that the browser has to remember this mapping, and in Tor Browser that mapping could be used to track or correlate you. Preloading the mapping would solve this, but how to preload the mapping probably brings us back into the realm of a browser extension.

Idea 2.5) Smart browser bookmarks for onion addresses

Talking about random addresses, it's funny how people seem to be pretty happy handling phone numbers (big meaningless random numbers) using a phone book and contacts on their devices.

On the same note, an easier but less usable approach would be to enhance Tor Browser with some sort of smart bookmark/petname system which allows users to register custom names for onion sites, and allows them to trust them or share them with friends. Unfortunately, it' unclear whether the user experience of this feature would make it useful to anyone but power users.

Of course it's important to realize that any approach that relies on a browser extension will only work for the web, and you wouldn't be able to use it for arbitrary TCP services (e.g. visiting an IRC server)

Idea 3) Embed onion addresses in SSL certificates

So let's shift back to non-browser approaches!

Let's Encrypt is an innovative project which issues free SSL certificates in an automated fashion. It has greatly improved Internet security since now anyone can freely acquire an SSL certificate for their service and provide link security to their users.

Now let's imagine that Let's Encrypt embedded onion address information into the certificates it issues, for clients with both a normal service and an onion service. For example, the onion address could be embedded into a custom certificate extension or in the C/ST/L/O fields. Then Tor Browser, when visiting such an SSL-enabled website, would parse and validate the certificate and if an onion address is included, the browser would automagically redirect the user. Take a look at this paper for some more neat ideas on this area.

Idea 4) Embed onion addresses in DNS/DNSSEC records

A similar approach could use the DNS system instead of the SSL CA system. For example, site owners could add their onion address into their TXT or SRV DNS records and Tor could learn to redirect users to the onion address. Of course this approach only applies to operators that can afford a DNS domain. Oh yeah DNS also has zero security...

Conclusion

As you can see there are many approaches that we should explore to improve usability in this area. Each of them comes with its own tradeoffs and applies to different users, so it's important that we allow users to experiment with various systems and let each community decide which approach works best for them.

It's also worth pointing out that some of these approaches are not that hard to implement technically, but they still require lots of effort and community building to really take off and become effective. Involving and pairing with other friendly Internet privacy organizations is essential to achieve our goals.

Furthermore, we should think carefully of unintended usability and security consequences that come with using these systems. For example, people are not used to their browser automagically redirecting them from one domain to another: this can seriously freak people out. It's also not clear how Tor Browser should handle these special names to avoid SSL certificate verification issues and hostname leaks.

One thing is for sure: even though onion services are used daily by thousand of people, the random addresses confuse casual users and prevent the ecosystem from maturing and achieving widespread adoption. We hope that this blog post inspires researchers and developers to toy around with naming systems and take the initiative in building and experimenting with the various approaches. Please join the [tor-dev] mailing list and share your thoughts and projects with us!

And this brings us to the end of this post. Hope you enjoyed this issue of Cooking With Onions! We will be back soon, always with the finest produce and the greatest cooking tips! What would you like us to cook next?

[Thanks to Philipp Winter and Tom Ritter for the feedback on this blog post, as well as to everyone who has discussed and helped develop these ideas.]

Great article! In practice I only regularly visit 3-4 onion addresses (by copy pasting them from onion.txt on my desktop). But I think at least 1/16 of the other sites I visit already have an onion service, but since finding onion services for them and classifying them in my txt file will take more time, I tend to just use the regular websites themselves.

One problem though: when I last tested adding specific HTTPS Everywhere rulesets to change addresses to their corresponding onion site (in the specific folder dedicated to user rulesets), it just didn't work. Is it just me or does it no longer work?

if anyone is interested I could share my own list of up-to-date rulesets, I was the major contributor to that project and I currently have around 300 rules which is twice the number in darkweb-everywhere, though many old rules contain dead websites

I don't know if such a thing exists. The proof of work is the whole reason NameCoin works. Clients never have to compute it so I don't think it's a big deal. In fact, there are already some public DNS servers that resolve .bit names (but you have to trust them).

So if you used Namecoin you would have to go to reddit.bit.onion .
And if you used GNS you would have to go to reddit.gnu.onion .
And if you used MagicalNameSystem you would have to go to reddit.mns.onion .

The idea here is that keeping the .onion TLD is very rewarding for Tor, since we have already registered it with IETF and it's protected. So no one can steal it from us, and also other browsers know that it's special-purpose and they shouldn't leak it to the DNS servers. e.g. see:https://bugzilla.mozilla.org/show_bug.cgi?id=1228457

as i understand dark-web-everywhere as in compare to the clear-net https-everywhere... should not be an worry if one trust the end website ? (assuming non-state honeypots)

depend on one own threat model i guess ...hidden to hidden you get the anon anyway... unless of course if one silly enough to give social information e.g with own name etc... and the hidden is an state run hidden service.

#1 is obviously the best. Okay that might be an overstatement, but really, all the alternatives pale in comparison. They either are browser only, require existing clearnet presence (DNS, PKI), or have real logistics/management hurdles (Zokoo's triangle).

We already have naming systems that are secure, human readable, and globally unique. Why would we bother with the registration politics nightmare of a remote authoritative naming repository? Or many nonauthoritative ones that can have global naming collisions.

NameCoin/GNS/BlockStack might even mainline the client code to make it compatible with Tor. And if not, a small shim would be super simple (disclaimer: I have not read the spec yet). Doesn't NameCoin already have a a record type reserved for .onion addresses?

The answer has been right in front of our faces for at least 5 years now (NameCoin, maybe even others before that). I honestly can't believe it has taken this long to get to where we are, and we're still in the proposal stage. But I'm glad we're getting there! This is a huge step for onion services!

Thank you for the links! As usual, the devil is in the details. But just from reading those two posts I can see the problem is not insurmountable. What was getting at is that #1 is the Right Way™ to solve the problem, not the easy way.

Why not try a system similar to PascalCoin, written in FreePascal.............Just like the nodes who carry Tor bandwidth mirror the directory why not create another directory written like PascalCoin and checked through a Tor directory. I2P is far ahead of Tor in this space, even though Tor has more users.

Why this "PascalCoin"? Does it have anything to do with a name system at all? It would take enornous effort to modify the codebase to work as a name system, as opposed to using an API like NameCoin's. And why does the language matter? Other than the fact that most of Tor devs already use C and JS and not Pascal.

Having the Tor directories do the lookups is an interesting idea. You'd have to trust them, and I don't know what the anonymity implications would be. You could do remote lookups for any other name system, like NameCoin, too.

I2P is not far ahead of Tor here. The I2P name system is actually kind of silly when you look at how it works. It's really nothing more than a remote replicated "hosts" file. It is not globally unique. And it has practical issues, for example names can never be freed for reuse, even if their private key is destroyed. It's a gimmick compared to NameCoin.

Oh, and by the way, a module could use or be based on PascalCoin or anything else. This blog post is about the API that connects Tor to name system modules. How the modules are implemented doesn't really matter. For all intents and purposes, Tor sees PascalCoin the same way as NameCoin.

Your just gonna have to make 2 directories one for private .Onions and one for .Onions who people post all over the net trying to direct people to. I don't think you can handle both without 2 seperate directories.

Create a public directory and keep the same .Onion system in place now if possible where someone can give their long string .Onion and either post or it keep it private. That seems like the best way to go, but people will want assurance that the public directory is not tampered with...............

Why you don't explore such an obvious approach to improving usability as various graphical representations of onion addresses? It works for security verification codes in WhatsApp, Telegram etc., it should also work for onion addresses.

Would it be possible to lift out just the tor dns code, and the nat traversal code for a dns system only? I like tor, but using a hidden service as a distributed and free dns is a superhit!

So in my ideal world, I'd like to have a Tor DNS software package, that enables me to have a constant .onion address for my home server that I can always use, and to avoid having to many hops in between.

I don't need anonymous browsing for my home server, but only an unchanging name.

Anyway, don't know if you have the time and resources to do this, but it would be nice. Thank you for all the good work!

check out the 'Single Onion Services' feature. It's a type of onion service with no anonymity on the service-side, so it doesn't use a 3-hop circuit on the service-side which means it should be faster, but still give you the static onion address you are looking for.

Thank you very much, I wasn't aware of that! =) That's a great option, and the only thing missing is the ability to disable the 3 hops on the client side as well (or perhaps 2 hops since I assume one hop is needed for routing purposes?).

But I can see that there is a possibility to tweak the countries the 3 hops are located in, so I think the performance should be more than enough for most use cases.

The latest financial reports for The Tor Project on the website only cover the period through the end of 2014. Do you know when the organization's 2015 and/or 2016 IRS 990 forms or audited financial statements will be made available? Thanks!

This idea is bad because it forces you to use hidden service verion of the website and in case of Facebook if you try to comment on news websites that facebook for comments under their articles you cant comment when you are logged in to facebook's hidden service.

Of course under normal Tor Browser privacy settings you can't comment even if you are logged in to clearnet Facebook website because of cookie isolation but if you enable third party cookies and tracking you can but as I said this doesn't work with Facebook's hidden service.

Would .tor be the official TLD for plain-text onion names? If so, do you have plans to get ICANN to assign special-use status to the TLD?
Would .tor be eligible for HTTPS certificates? If so, would it support domain validated like Let's Encrypt or EV only.

That said, would the next generation strong .onion addresses support DV certificates, adding the possibility of Let's Encrypt being able to add support per CA/B rules?

.tor was just an example for this blog post.
We have not actually decided what to do about the tld, but we probably gonna go with .onion . So, like .tor.onion, or .bit.onion, etc. Exactly for the reason that ICANN has standarized .onion and we should keep ourselves in that zone (see other comments on this topic).

We are hoping that the CAB forum will allow onion addresses to get DV certificates as well. I think there are some discussions underway right now, but I imagine the next gen onion services will put extra pressure here.

I am of the opinion that the optimal scheme is one where I'd be able to boot some amnesic OS that includes Tor and type an "onion" address from memory, just like typing facebook.com of microsoft.com. Nothing written down. Nothing to connect an address to me.

Namecoin as it stands requires users to download a blockchain to use it, this is very stupid. I will never download a blockchain, not for any coin or reason, at least not through Tor.

Centralized registries are also stupid, this makes the registrar liable, might as well just petition icann to handle all of this.

We would need a decentraized dns free of blockchain bloat. It seems like the existing onion addressing and network handling already works to this advantage except that it relies on the fact that no two names will ever collide. In which case why not allow people to register collisions then use existing onion network measurement tools to determine the popularity of sites, returning them in the same way a search bar returns autosuggestions.

For privacy reasons it would be great if the DNS information of the blockchain could be integrated into the tor network, so that it is not necessary to access the public nameserver out of the tor network.

Blockchain technology is perfect for this purpose as it provides a maximum transparent and secure way to resolve the issues discussed.

As a user you do not have to download the whole blockchain (which is also no big mess for a blockchain containing the DNS system of Tor; it's mainly static data); you can work with a pruned blockchain or use a web based service.

Setting up a tiny fee on each DNS modification prevents massive abuse as no-one likes to burn money. That's perfect for an anonymous network like Tor.

A public blockchain explorer containing all confirmed blockchain operations is like a public dictionary offering a level of trust for every user.

Tor is only missing an interface providing direct access to the public DNS data of Namecoin or 611 so that it's not necessary to poll external DNS servers (which can be subject to external influence) to resolve domain names stored in the blockchain.

NameCoin doesn't work without the blockchain. Zokoo's triangle is a hard problem, and it just so happens NameCoin is one of the very few things (maybe the only thing) that actually solves it. We would all like a globally unique, secure, and human readable naming system that doesn't require the user to download a blockchain... we're just waiting for it to be invented at the moment.

This blog post made it pretty clear that the traditional .onion addresses aren't going anywhere, although they may be increased to 54 characters. All of these proposals are extensions on top of that. Idea #1 allows for many different naming system modules to be used, so you can just use the ones you like the best. Nobody is forcing anyone to use anything.

Hi! There's a new alpha release available for download. If you build Tor from source, you can download the source code for 0.3.3.2-alpha from the usual place on the website. Packages should be available over the coming weeks, with a new alpha Tor Browser release some time in February.

Remember, this is an alpha release: you should only run this if you'd like to find and report more bugs than usual.

Tor 0.3.3.2-alpha is the second alpha in the 0.3.3.x series. It introduces a mechanism to handle the high loads that many relay operators have been reporting recently. It also fixes several bugs in older releases. If this new code proves reliable, we plan to backport it to older supported release series.

Changes in version 0.3.3.2-alpha - 2018-02-10

Major features (denial-of-service mitigation):

Give relays some defenses against the recent network overload. We start with three defenses (default parameters in parentheses). First: if a single client address makes too many concurrent connections (>100), hang up on further connections. Second: if a single client address makes circuits too quickly (more than 3 per second, with an allowed burst of 90) while also having too many connections open (3), refuse new create cells for the next while (1-2 hours). Third: if a client asks to establish a rendezvous point to you directly, ignore the request. These defenses can be manually controlled by new torrc options, but relays will also take guidance from consensus parameters, so there's no need to configure anything manually. Implements ticket 24902.

Major bugfixes (netflow padding):

Stop adding unneeded channel padding right after we finish flushing to a connection that has been trying to flush for many seconds. Instead, treat all partial or complete flushes as activity on the channel, which will defer the time until we need to add padding. This fix should resolve confusing and scary log messages like "Channel padding timeout scheduled 221453ms in the past." Fixes bug 22212; bugfix on 0.3.1.1-alpha.